Project Summary Stroke is a leading cause of death and disability in the US, and its impact will further increase as the population ages. Whereas left-brain stroke (LBS) often dramatically affects language and right hand use, right-brain stroke (RBS) spares them, despite virtually identical lesion sizes and types. Nevertheless, people with RBS are less likely to resume independent lives, suggesting that cognitive impairments are more disabling after RBS. This research will focus on emotion recognition, which is attributed to the right hemisphere and often impaired after RBS, but is poorly understood and rarely assessed or addressed in rehabilitation. We hypothesize that emotion recognition impairments (ERIs) after RBS have a disproportionate effect on return to independence because they interfere with stroke survivors' ability to maintain and forge interpersonal relationships. This leads to a loss of social support, a crucial determinant of return to independence, health outcomes and social participation. We further hypothesize that differences in ERIs after stroke are not only driven by what tissue is lesioned, but also by whether (and which) non-lesioned tissue is recruited to compensate for the loss (i.e., functional reorganization/plasticity). As non-invasive brain stimulation now enables us to enhance the activity of specific brain areas as a person (re-)learns a skill, knowing which brain areas can contribute to emotion recognition after stroke opens up the possibility of augmenting behavioral training through neurostimulation. To test our hypotheses, and to thus lay a foundation for clinical treatment of ERIs, we will 1) Assess emotion recognition abilities, social support, and long-term outcomes in participants with RBS and LBS (to assess the effect of lesion site), and neurologically healthy control participants matched for age, sex, and socioeconomic status to determine the relationships between these variables. 2) Perform functional and anatomical magnetic resonance imaging (MRI) in the same participants to determine which specific brain areas are normally involved in emotion recognition, how lesions to these areas affect emotion recognition, and which other brain areas might compensate for the lost tissue. If our hypotheses are correct, these data will (1) demonstrate the role that emotion recognition impairments play in determining long-term outcomes after stroke, and (2) provide the basis for developing improved diagnostic tools and targeted interventions based on each individual's functional neuroanatomy. Given the success of emotion recognition training in both healthy individuals and those on the autism spectrum, such training augmented by targeted neurostimulation could be a promising new rehabilitation approach for RBS and other causes of ERIs, especially traumatic brain injury. This work will support the development and larger- scale evaluation of such an intervention, and pave the way for improved emotion recognition needed to support social roles (especially marriages and employment) in persons with acquired brain injury.